Every April, Shelby White kicks off the Open Days garden-touring season in the Lower Hudson Valley by throwing open the gates of her phenomenal 45-acre woodland estate in Lewisboro. This year, the White Garden will be open 10 a.m.-3 p.m. April 28. If you fancy daffodils — as in more than 500,000 of them scattered among the rolling lawns and wooded pathways — this is your way to discover how great the Garden Conservancy’s Open Days Program can be.

Quite simply, it’s one of best ways going to play tourist in your own town. It’s not some cliquish, insider garden party that anyone should feel intimidated about. It’s just plain folks in their weekend duds, not a bunch of ladies with stylish hats. You simply pay $5 at the gate for a chance to wander around some of the best private gardens in the country that are open for a single day a year. A few gardens open a second day in the fall.

You can just go to one garden that day, or you can clump a few together and make an afternoon of it. It’s your choice, at your pace, in your own car.

Maybe it’s the topography or maybe it’s the money, but Westchester boasts some of the best private gardens in the whole Northeast. This year, 18 private gardens in the county are taking part in the Open Days Program, along with two in Putnam. Alas, there are no Open Days in Rockland this year, but Bergen County, N.J., has gardens open on May 11 and June 23.

It’s not just about gardens, folks. You’ll see some killer real estate (exteriors only) and likely come away with innovative ideas for your own yard about planting combinations, swimming pools, decking, stone walls, fencing and how to hide your neighbor’s ugly garage. Bring a camera and a notebook. And wear sensible, closed-toe shoes. Some gardens are formal and paved, but others are rather knobby and rugged. Don’t forget bug spray, sunscreen and a hat.

I recommend picking a few Open Days farther up the Hudson Valley as an excuse to go motoring for the weekend and get out of your own yard and away from your endless chore list. There are fantastic estates and gardens in Dutchess, Columbia and Ulster counties that participate in the Open Days Program. Go antiquing in Hudson or Rhinebeck and and stop at two or three gardens along the way. Fantasize about a weekend home or where you might retire.

I also recommend making a plan now by spinning through the Conservancy’s Open Days Directory or their well-organized website (www.gardenconservancy.org/opendays). Before you know, it will be July and the best gardens are long gone.

Meanwhile, this spring looks to be a winner at the White Garden, unlike last year when early warm weather sent the daffodils into bloom well before their Open Day.

“This year is going to be gorgeous,” says Eric Schmidt, the head gardener at the White Garden and the workhorse who digs in thousands of new daffodil bulbs every fall. “The weather is just right to have all the daffodils all in bloom and some of the flowering trees like the weeping cherry and pear. It should be a stunning year.”